1. Technical Field
The present invention relates to a liquid ejecting head of an ink jet type recording head or the like, and particularly, to a liquid ejecting head for discharging a liquid in a pressure generating chamber out of a nozzle orifice by giving a pressure fluctuation to the pressure generating chamber which is in communication with the nozzle orifice.
2. Related Art
As a liquid ejecting head for discharging (ejecting) a liquid droplet out of a nozzle orifice (one kind of a nozzle) by generating a pressure fluctuation at a liquid in a pressure generating chamber, there are, for example, an ink jet type recording head (hereinafter simply referred to as a recording head) used in an image recording apparatus such as an ink jet type recording apparatus (hereinafter simply referred to as a printer), a color material ejecting head used in manufacturing of a color filter of a liquid crystal display or the like, an electrode material ejecting head used in forming of an electrode of an organic EL (Electro Luminescence) display, FED (Field Emission Display), or the like, a bioorganic matter ejecting head used in manufacturing of a biochip (a biochemical element), and the like.
For example, the above recording head is constituted by mounting a flow path unit in which a series of liquid flow paths extending from a reservoir to a nozzle via a pressure generating chamber are formed, an actuator unit having a pressure generating element capable of varying the volume of a pressure generating chamber, or the like to a head case made of resin. A nozzle plate made of a metal (one kind of a nozzle forming member) in which a nozzle is formed is bonded to the flow path unit.
A liquid to be discharged from the recording head as described above has a viscosity suitable for discharging, for example, such as approximately 4 mPs·s, etc. at a normal temperature according to the kind of a liquid. Since the viscosity of a liquid correlates with a temperature, there is a characteristic that the lower a temperature is, the higher a viscosity is, and the higher a temperature is, the lower a viscosity is. On that account, there has been proposed a recording head provided with a temperature regulating portion for heating (or cooling) a liquid in the case where a recording head designed to be suitable for a viscosity of a liquid used usually is put in low temperature (or high temperature) environment, the case where the recording head discharges a liquid having a high (or low) viscosity, or the like (For example, refer to JP-A-2001-270090).
The temperature regulating portion is formed into a ring shape, and disposed in proximity to a portion of a series of liquid flow paths extending to the nozzle, thereby to directly heat (or cool) a liquid in the liquid flow path. On that account, even the inside of the liquid flow path, a portion not being in proximity to the temperature regulating portion could not heat (or cool) efficiently a liquid to a desired temperature. That is, in the recording head having such a construction, it takes long time until a temperature of a liquid in the liquid flow path is adjusted to a desired temperature, whereby it could not be put to practical use. Further, for efficient heating, it was necessary to dispose the temperature regulating portion in close proximity to the liquid flow path and also, over a long length.
However, if distance between the liquid flow path and the temperature regulating portion becomes more distant, a thermal conductivity is low and also, a direction being transmitted cannot be controlled, whereby, it was not possible to efficiently heat (or cool) a liquid in the liquid flow path. Further, in the case of intending to dispose the temperature regulating portion in close proximity to the liquid flow path and also, over a long length, since there is put limitation on the disposition, there was a fear that the recording head will be made larger, or the degree of freedom of a shape of the recording head will be impaired.